Some clarifying for those who are confused...
Spoilers ahead obviously!
Ok so I keep reading how they left out all this stuff and how people are confused, not sure how bc I pretty much understand everything on one viewing but maybe some people aren't as use to how homicide cases unfold as I am.
Ok so Anne's mom was a drug addicted hooker using her house to do guys, so she always kicked Anne out. Anne only sold things or got in trouble bc she was trying to survive her poverty stricken life, and her upset stomach she always had, probably from malnutrition. (People keep askin why she needed that, milk of magnesia is for upset stomach) but generally she was a good girl just tying to survive.
Lavon and white dude killed Debbie mills, who was ne of their hookers, probably she hid $ from them and they accidentally beat her to death, just a guess. anyway the car they hid in the black ladies garage had her DNA on it so they kidnapped the black lady knwn as 'mama or whatever she was called, daughter, as a hostage. This was just another homicide case they were working on during the movie to show how the any cop isn't interested in small time stuff (Ill explain further down) and to confuse the viewers as to who is really the killer.
Kristin Lanes murder was done by the creepy mill worker dude, and bc Anne was always with the cops he made the brother go with him to kill her too, that's why they had Kristin lanes cell phone etc, so the creepy dude with glasses was the serial killer of the fields, for the recent murders anyway
Notice the first homicide was not found in the fields, it was outside some rundown neighborhood in the main detectives actual jurisdiction
The partners ex-wife is the only detective whose actual jurisdiction was the killing fields, but I guess since the two main detectives are supposed to be such awesome detectives ( or atleast I assume that's what their intentions for her borrowing them were) she was always asking them for help on the serial cases.
Everything was pretty much explained pretty clearly if you pay attention, I'm not sure why everyone keeps commenting its so confusing, they showed it like an actual case folds out, from the start you are thrown in not knowin much about the victim or circumstances, and you go from there. Everything revealed itself tho so unless they literally spelled it out idk what more people want! Your not meant to know more than what's shown about the cops' backgrounds, but it does give you some insight into their lives, the one from NY obviously was tortured by an unsolved serial murder case, and about not being able to save a victim,(he recalls this to his wife if you paid attention) but the story wasnt about that case, it's only brought up to show viewers why he is so hell bent & determined on helping the serial murders of the killing fields instead of worrying about two-bit pimps like lavon and rule. (As I mentioned earlier why they were part of the movie
The other dude obviously was married to the other girl detective and that's hopefully self explanatory... Ok hope that helps!